I am attempting to find the relation between the 5.19 values I receive and the strength of the signal that I input. When I put in a 1 V rms signal I get the values of 0x00, 0x79, 0xdf, 0x6b which when converted from hex to integer is 7987051, but when I put in a .5 V rms signal I get a value of 0x00, 0x72, 0x13, 0xF4, which when converted from hex to integer is 7476212. So the relation between those two values is 0.936 rather than 0.5. Is there some equation that relates these two values?

Any help is much appreciated. Thank you.

Hello,

The cell you are using has a built-in filter that limits the measurement to a certain frequency band. This means that the readback level will vary depending on the frequency content of your input signal. You can change the filter by clicking on the small red "Wnd" button in the lower left corner of the cell.

To get a frequency-independent level measurement, please try using the running average cell (plus the DSP readback cell) as described in this thread: http://ez.analog.com/message/7669

In particular, check out the Envelope Implementations section of that thread.

Also note that the ADAU1761's readback format is 5.23, not 5.19, so you have some additional accuracy on the low end.